This invention concerns a watch case comprising a middle containing a lining of synthetic material and at least one part detachably mounted in the opening of the middle by means of a pressure device, as well as a process to manufacture such watch case.
Swiss Pat. No. 616,808, as well as Swiss patent application No. 632,890 G, describe watch cases, the middle of which is lined with a synthetic material, e.g., by a molding process, and which are equipped with a bezel or a detachable back capable of being set in place under the effect of simple pressure. The value of these designs lies in simultaneously sealing the middle at all of its opening, notably, also at the passage of the control stem, and also to assure the elastic suspension of the movement. However, in these known watch cases sealing of the opening provided for the bezel or the back could be accomplished only by radial compression of the lining flush around the opening or its deformation by a hook-shaped skirt provided on the periphery of the bezel or back. To guarantee perfect tightness, it has proven necessary to provide sufficient depth of engagement of the bezel or back inside the middle, which is not always compatible with the dimensions of the extra-flat watch parts known at present. Furthermore, the axial retention of the bezel or of the back and the compression they exert on the seal are not as good as for the standard cases, where, for example, the outer surface of a skirt of the back or of the bezel comes in contact with an inclined metal surface of the middle.